Unloading means for a reciprocating compressor



Feb. 14, 1961 A. J. NICHOLAS 2,971,690

UNLOADING MEANS FOR A RECIPROCATING COMPRESSOR Filed Oct. 24, 1958 s Sheets-Sheet 1 FIG.]

ANDREW I NICHOLAS INVENTOR. BY M M J 6 Feb. 14, 1961 A. J. NICHOLAS 2,971,690

UNLOADING MEANS FOR A RECIPROCATING COMPRESSOR Filed Oct. 24, 1958 3 Sheets-Sheet 2 FIG. 2

ANDREW I NICHOLAS INVENTOR.

Feb. 14, 1961 c cL s 2,971,690

FIG. 3

ANDREW I NCHOLAS INVENTOR.

W MM United States Patent UNLOADING MEAYS FOR A 'RECIPROCATING CONIPRESSOR Andrew J. Nicholas, Sulfield, 'Conn., assignor to Worthington Corporation, Harrison, N.J., a corporation of Delaware Filed Oct. 24, 1958, Ser. No. 769,364

9 Claims. (Cl. 230-30) This invention relates to reciprocating compressors and more particularly to unloaders associated therewith to vary the capacity thereof.

It is an object of the present invention to provide a simple, practical and positive unloading mechanism for reciprocating compressors.

It is a further object of the present invention to provide an unloader means which has relatively few parts and hence can be manufactured at less cost, can be assembled outside the compressor as a sub-assembly, easily installed without misalignment, is easily removed and disassembled when repairs become necessary, and is fabricated with minimum moving sealing parts which seal on large surface areas to thereby substantially reduce stickmg.

Another object of this invention is the adaptation of a bellows means, surrounding a removable liner, to act as the means for holding the suction valve open in a reciprocating compressor.

With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, show various unloader means, all embodying a resilient fluid-containing chamber, associated with a reciprocating compressor, and the features forming the invention will be specifically pointed out in the claims.

In the drawings:

Figure 1 is a fragmentary vertical section showing the unloader means contemplated by this invention.

Figure 2 is a fragmentary vertical section showing the unloader means contemplated by this invention.

Figure 3 is a fragmentary vertical section on different planes showing'another modification of-theunloader and the springs associated therewith to amplify the action of the resilient fluid-containing chamber.

Referring to the drawings, Figure 1 shows a portion of the casing generally designated 1 and the head 2 of a reciprocating compressor. An upper bulkhead 3 and a lower bulkhead 4 form a suction manifold 5 in the casing 1 separated from the crankcase 6. The head 2 forms a discharge manifold 7 with the upper bulkhead 3 when in the assembled position.

While Figure 1 illustrates only one cylinder it will be understood by those familiar with this art that the present arrangement may be used in single or multi-cylinder reciprocating compressors.

Broadly, Figure 1 shows an elongated cylindrical liner- 8 having a flange 9 disposed about its upper end. The outer edge of the flange in assembled position having a sliding fit with the opening 10 formed on the upper bulkhead3. The lower end of the cylinder liner 8 has a slip fit with opening 11 in the lower bulkhead 4', of lesser diameter but in alignment with the opening 10 in the upperbulkhead 3.

The upper or outer face of the flange 9 is connected to ,a valve plate 12 as by threaded means 13 so that an annular face is formed as at 14 which engages a shoulder 15 formed by the opening 10 and the upper or outer face of the upper bulkhead 3. Thus the valve plate acts to support the cylinder liner.

The cylinder liner 8 and valve plate, however, are further fixedly positioned to the compressor housing 1 by means of a discharge valve housing 16, including the usual discharge valve arrangement as is described in detail in copending application Serial No. 741,254 filed June 11, 1958,disposed in engagement with the upper or outer face of the valve plate 12. Threaded members 17 extend through the discharge valve housing and the valve plate 12 to threadably connect these elements in assembled position relative to the upper and lower bulkheads, as is clearly shown in the drawings.

A piston 18 is adapted to be reciprocated in conventional manner in the cylinder formed by the cylinder liner as at 19 by means of a piston rod and a crankshaft driven by any suitable prime mover (not shown) such as a constant speed motor. Inwardly of the periphery of the flange 9 a plurality of circumferentially spaced suction inlet ports 20 provide communication between the suction manifold 5 and a suction valve chamber 21. The suction valve chamber 21 communicates in turn with the cylinder 19 and fluid will flow from the suction manifold 5 through the ports 20, chamber 21 to the cylinder in 1 accordance with the position of an annular suction valve strip 22 disposed in the valve chamber and held in position by suction valve springs 23 as is clearly shown in the drawings.

A discharge chamber 24 communicates with the cylinder 19 and the discharge manifold 7 through the usual discharge valve and port arrangement as is described in detail in copending application mentioned above.

When the compressor is loaded inward movement of the piston 18 causes the discharge valve strip (not shown) to close and therefore prevent fluid flow thereto to the discharge manifold, and gas to flow from the suction manifold 5 through the suction inlet ports and suction valve chamber to the cylinder. After the piston reaches bottom dead center and starts to move upwardly the compressor compresses the fluid in the cylinder causing the annular suction .valve strip 22 to close the suction inlet ports 20 and the discharge valve to open and the compressed fluid to be forced out against the pressure of the gas in the discharge manifold through the usual ports and valving arrangement formed in the discharge valve housing to the discharge manifold from there to its use.

In order to operate the compressor at substantially constant speed but at increments of its full capacity one or more of the suction valve strips 22 are held in an open position so that the cylinder associated with this valve strip will be unable to deliver compressed gas to the discharge manifold as above described.

This is accomplished by an unloader assembly generally designated 30 and shown in the drawings as mounted 1 in the suction manifold 5 about and relative to the cylinder liner 8 and fitting in an annular groove 31 formed in-the lower bulkhead 4 about the opening 11.

The unloader assembly is guided and aligned during the assembly of the various elements by means of an operating fluid connecting means 32 referred to in detail hereinafter.

The unloader' assembly coacts with a plurality of suction valve strip lifting pins 33, referred to as actuating means, which are circumferentially disposed about the cylinder liner 8 and mounted for slidingmovement in the corresponding suction inlet ports 2%, the pins having suflicient length to hold the valve 22 in open position when the movable means 34 of the unloading assembly 30 engages the head 35 of the pins as hereinafter described.

..Springs .36 are mounted about. each of the pins 33.

between the inner or lower face of the flange 9 and the head 35 of the pin. In loaded position the springs will move and hold the pins out of engagement with the annular suction valve strips 22 and will be compressed when the compressor is in the unloaded position to coact in holding the annular suction valve strip 22 in open position. a

.The unloader assembly 30 is of relatively simple construction. In the form shown in Figure 1 it comprises broadly a resilient fluid-containing chamber 36 mounted toreceive fluid from the fluid supply source as at 39 and has associated therewith movable means 34 which abut the valve actuating means or pins 33 which load or unload the suction valve 22 depending upon whether fluid is supplied to or removed from the resilient fluid chamber 36. The resilient fluid'chamber 36 comprises upper and lower annular rings 37 and 38 mounted about the cylinder liner 8 in superposed relation and fixed thereto, the lower annular ring 38 having passageways 39 formed therein which communicate with the fluid supply source 40 which is usually the lubricating system of the compressor.

Bellows members 41 and 42 are fixed to the upper and lower rings and the free ends 43 and 44 thereof adapted to be connected to the movable means 34 and to provide a sealed fluid-containing chamber having resilient qualities.

ring is accomplished through the provision of a slot 88 cut on the upper end thereof and whose dimensions are determined by the extent of movement required. A pin 89 fitting into the ring 80 extends into the slot 88 to limit the movement of the unloader to that desired'in the application.

It will be understood that the invention is not to be 7 limited to the specific construction or arrangement of Seals 45 and 46 are mounted in slots 47 -and48 in both of the. rings to further provide for a positive sealing of the chamber 36.

The movable means 34 comprises a ring '49 having a post 56 thereon at QneLend to function to coact with the face 51 to limit the travel of-the movable means. A cylinder 52 having a flange 53 is mounted on the other end of the movable means and as is shown in the drawings on a shoulder 54 formed thereon, the flange forming a rest or perch for the pins 33.

In operation the bellows means normally acts to hold the'movable means in abutment with the pins 33 which in turn'hold the suction valve open and thus the cylinder is unloaded. When proper conditions occur or when desired fluid is caused to flow through the pipe 40 into the resilient chamber 36 to thereby'cause an extension of the bellows in a downward direction. This follows by virtue of the eifective mean radii R and R of, the bellows which is suificient-to cause the required downward movement. 7

Figure 2 shows another form of the invention which differs from the form shownin Figure 1 only insofar.

as a sleeve 70 is provided for the liner 8 to therefore eliminate the need of sealing the' upper ring 37. f

Accordingly it is thought that since the operation and construction are very much like the unloader shown in a Figure '1 that the construction and'operation of this form is clearly understood from the above description concern ing the foregoing unloader.

Figure 3 shows another modified form of the invention and in describing this formof the inventionparts which are identical to those in Figure 1 have been given the same characteristics and those parts and their operation are deemed to operate in the same manner as above described, and the descripiton of this form of the, invention will accordingly be limited to the unloader assembly per 'se and the relationship of this assembly to. 'the'other components of the compressor above described which difiers from theform of the operation of the unloader assembly shown in Figure l.

Thus, the resilient fluid chamber comprises a fixed,

as by S-ring 80 to the liner 8, ring 81 and resilient bellows parts shown but that they may be widely modified within the invention defined by the claims. a

What is claimed is: V

'1. Unloader means 'for varying the capacity of a reciprocating compressor including a casing, a cylinder in said casing, a piston slidably disposed in said cylinder,

a suction inlet and a discharge outlet for said cylinder and having valve means operatively associated therewith to control fluid flow into and out of said cylinder, said unloader means comprising an annular resilient fluid-containing chamber mounted about said cylinder and concentric therewith, fluid supply means operatively connected to said resilient fluid-containing chamber and for supplying a source of fluid thereto, movable means about said cylinder and operatively connected to said resilient fluid-containing chamber, and Valve actuating means disposed on saidmovable means and in abutment with said suction valve means whereby upon supply of fluid to said resilicntrfluid-containing chamber said movable means moves said valve actuating means out of abutment with said suction valve means.

2. The combination claimed in claim '1 wherein the resilient fluid-containing chamber comprises an upper annular ring mounted about the cylinder, a lower annular ring mounted on the'fluid supply means and plural bellows means connected to each of said rings to form a fluid-containing chamber, and the movable means operatively connected to each of said annular rings comprises a cylindrical ring having a flange at the upper end for supporting the valve actuating means. 7

3."I he combination claimedin claim 2 wherein the lower annular ring includes springs disposed therein to increase the resiliency thereof.

4. The combination claimed in claim 1 wherein the resilient fluid-containing chamber comprises an upper annular ring mounted about the cylinder, a lower annular ring fixed to the casing and about the cylinder, resilient bellows means connected to each of said rings and forming free ends and the movable means including an annular ring for operatively interconnecting the free ends of the bellows means and to form a fluid-containing chamber between the bellows means and the cylinder.

5. The combination claimed in claim 4 wherein the movable means includes a cylindrical ring fixed to the annular ring and having a flange on the upper end for supporting the valve actuating means in operative position. V

6. The combination claimed in claim 5 wherein a cylindrical sleeve is'disposed between the flexible fluidcontaining chamber 'and the cylinder.

7. Unloader means for varying the capacity of areciprocating compressor including a casing, a.v cylinder in said casing, a piston slid-ably disposed in said cylinder, a suction inlet and a discharge outlet for said cylinder and having valve means operatively associated therewith'to control fluid flow into and out of said'cylind'er, said unloader means comprising a resilient fluid-containing chamber having a body portion including plural annular rings spaced from each other andmounted about said cylinder andfconcentric therewith, and resilient bellows means operatively connectedto each of said annular rings influid tight relation, fixed fluid supply means operatively connected to said resilient'fluid containing chamber and for supplying a sourceflof fluid thereto, movable means about said cylinder and operatively connected to said body portion, and valve actuating means disposed 'on the movable means and normallyin contact with said valve means to hold the valve means open and said movable means to remove the valve actuating means out of contact with the valve means during increase of fluid flow to said resilient fluid-containing chamber.

8. Unloader means for varying the capacity of a reciprocating compressor including a casing, a cylinder in said casing, a piston slidably disposed in said cylinder, a suction inlet and a discharge outlet for said cylinder and having valve means operatively associated therewith to control fluid flow into and out of said cylinder, said unloader means comprising a resilient fluid-containing chamber mounted about said cylinder and having an upper annular ring fixedly mounted about said cylinder and a lower annular ring mounted about said cylinder and spaced from the upper annular ring, plural bellows means each connected to one of said rings and forming free ends, a movable means comprising a cylindrical ring interconnecting the free ends of said bellows means to form a fluid-containing chamber between the bellows means and the cylinder, a cylinder including a flange at its upper end formed on the cylindrical ring, fluid supply means communicating with said fluid-containing chamber through said lower annular ring and for supplying a source of fluid thereto, and valve actuating means mounted on the flange of said cylinder at one end and in abutment with said suction valve at the other end whereby said movable means upon supply of fluid to said resilient fluid-containing chamber moves said valve actuating means out of abutment with said suction valve means.

9. The combination claimed in claim 8 wherein a cylindrical sleeve is disposed between the fluid-containing chamber and the cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 2,208,428 Nicolet July 16, 1940 2,555,004 Rinehart May 29, 1951 2,555,005 Warneke May 29, 1951 2,565,564 Lamberton Aug. 28, 1951 FOREIGN PATENTS 160,230 Australia Dec. 13, 1954 529,187 Canada Aug. 14, 1956 

